This invention relates to a composition and method of preventing fouling in (meth)acrylic acid processes. More particularly, this invention is a composition comprising (meth)acrylate or (meth)acrylamide antifoulant polymers, and use of the composition to prevent fouling in (meth)acrylic acid manufacturing processes and processes in which (meth)acrylic acid is used in a reaction and where unreacted (meth)acrylic acid is recovered.
(Meth)acrylic acids are monomers used to prepare many polymeric materials. However, their tendency to polymerize makes their manufacture, transportation and storage difficult. This is especially true in processes involving manufacturing and reclaiming the monomers, in which elevated operating temperature increases undesired polymerization. Under such circumstances, polymer formation becomes so severe that the polymer precipitates and fouls process equipment. Eventually, equipment shutdown and cleaning is required for removal of the polymeric foulant.
Conventionally, polymerization inhibitors are used in (meth)acrylic acid processes to prevent undesired polymerization. Typical polymerization inhibitors are phenolic compounds, amines, quinones, nitroxyl compounds and certain inorganic complexes. Phenothiazine (PTZ), hydroquinone (HQ) and monomethyl hydroquinone ether (MEHQ) are examples of the most widely used inhibitors. These inhibitors are designed to interrupt the polymerization reactions and prevent formation of the polymer. However, none of the available inhibitors are efficient enough to completely eliminate undesired polymer formation. Even in the presence of these inhibitors, polymer formation and subsequent fouling is still substantial, so that periodic cleaning is part of routine operation.
There is, therefore, an ongoing need to develop improved treatments, in addition to polymerization inhibitors, to control fouling in (meth)acrylic acid processes.
This invention is an antifoulant composition comprising (meth)acrylic acid and one or more (meth)acrylate or (meth)acrylamide antifoulant polymers, the antifoulant polymer prepared by polymerising
a) about 5 to 100 mole percent of one or more (meth)acrylate or (meth)acrylamide monomers of formula 
or a mixture thereof, wherein R1 is independently selected at each occurrence from hydrogen and methyl; R2 is selected from alkyl, aryl, cycloalkyl, alkylaryl, arylalkyl, aminoalkyl, aminoaryl, hydroxyalkyl, alkoxyalkyl, oxoalkyl and haloalkyl; and R3 and R4 are independently selected from hydrogen, alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, aminoaryl, hydroxyalkyl, alkoxyalkyl, oxoalkyl and haloalkyl, or R3 and R4, together with the nitrogen atom to which they are attached, form a heterocyclyl group; and
b) 0 to about 95 mole percent of one or more vinylic monomers.